The present invention relates to a method for making magnetrons. More specifically, the present invention relates to a method for making magnetrons used in radars, microwave heating devices, e.g., microwave ovens, or the like.
Referring to FIG. 4, a conventional magnetron includes a plurality of vanes 52 formed within a cylindrical anode cylinder 51. An anode vacuum container 55 includes a magnetic piece 53 and a metal container 54 disposed at the open end section of the anode cylinder 51. A cathode 57, disposed along the center axis of vacuum container 55, includes a top hat 56a, an end hat 56b, and a filament 56c. An antenna 58 extracts a microwave, e.g., at 2450 MHZ, generated in the hollow space. In this magnetron, the thermoelectrons discharged by filament 56c spin inside the active space formed between vanes 52 and filament 56c, generating a microwave. This microwave, flowing along a vane 52, is transferred to antenna 58 connected to vain 52. The microwave is then discharged externally through antenna 58.
Anode cylinder 51 and metal container 54 are bonded by tightly welding thin end section 59 of anode cylinder 51. Referring to FIG. 5(a), before the welding operation, thin end section 59 of anode cylinder 51 has a roughly even thickness between end 59a and base section 59b. Magnetic piece 53 and metal container 54 are placed on an inner shelf 60 of thin end section 59.
Referring to FIGS. 4 and 5(b), thin end section 59 of anode cylinder 51 is melted by welding to form a tight bond with outer perimeter bend 54a of metal container 54.
If a slight gap forms between the inner wall surface of thin end section 59 of anode cylinder 51 and outer perimeter bend 54a of metal container 54 due to dimensional tolerances, misalignment of the parts, or the like, this gap will remain, even after the tight welding. This can lead to reduced sealing properties. Discarding such assemblies results in increases material costs, while performing repairs of these assemblies increases the number of steps involved in the procedure.
To prevent these gaps, the parts may be formed with shapes that provide alignment relative to each other. If alignment between the parts is not possible, dedicated tools or equipment may be used to secure the parts while welding. However, with each of these methods there is an increase in production costs.
It is an object of the present invention to provide a method for making a magnetron which overcomes the foregoing problems.
More specifically, it is an object of the present invention to provide a method for making magnetrons that easily improves the quality of the tight welding operation.
Briefly stated, the present invention provides a magnetron having an anode cylinder, a plurality of vanes arranged radially within the anode cylinder, a magnetic piece disposed at an open end section of the anode cylinder, an anode vacuum container including a metal container disposed to cover an upper surface of the magnetic piece, a cathode disposed along a central axis of the vacuum container, and an antenna externally discharging microwaves. The magnetic piece and the metal container are placed, in that order, on a shelf formed inwardly on a thin end section projecting from the open end section of the anode cylinder. When tightly welding the thin end section, a predetermined number of projections, projecting inwardly from the thin end section of the anode cylinder, loosely secure an outer perimeter bend of the metal container. The metal container is then accurately tightly weld to the anode cylinder without the metal container shifting off-center.
According to an embodiment of the present invention, a method for making magnetrons includes a magnetron having an anode cylinder, a plurality of vanes arranged radially within the anode cylinder, a magnetic piece disposed at an open end section of the anode cylinder, an anode vacuum container including a metal container disposed to cover an upper surface of the magnetic piece, a cathode disposed along a central axis of the vacuum container, and an antenna externally discharging microwaves. The magnetic piece and the metal container are placed, in that order, on a shelf formed inwardly on the thin end section projecting from the open end section of the anode cylinder. When tightly welding the thin end section, a predetermined number of projections projecting inwardly from the thin end section of the anode cylinder is used to loosely secure an outer perimeter bend of the metal container.
According to another embodiment of the present invention, a method for making magnetrons includes providing a magnetron having an anode cylinder, a plurality of vanes arranged radially within the anode cylinder, a magnetic piece disposed at an open end section of the anode cylinder, an anode vacuum container including a metal container disposed to cover an upper surface of the magnetic piece, a cathode disposed along a central axis of the vacuum container, and an antenna externally discharging microwaves. The magnetic piece and the metal container are placed, in that order, on a shelf formed inwardly on the thin end section projecting from the open end section of the anode cylinder. When tightly welding the thin end section, a ring-shaped projection, projecting inward from the thin end section of the anode cylinder, is used to loosely secure an outer perimeter bend of the metal container.
The above, and other objects, features and advantages of the present invention will become apparent from the following description read in conjunction with the accompanying drawings, in which like reference numerals designate the same elements.